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Diffstat (limited to 'include/asm-s390x/semaphore.h')
| -rw-r--r-- | include/asm-s390x/semaphore.h | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/include/asm-s390x/semaphore.h b/include/asm-s390x/semaphore.h new file mode 100644 index 000000000..eda753caa --- /dev/null +++ b/include/asm-s390x/semaphore.h @@ -0,0 +1,191 @@ +/* + * include/asm-s390/semaphore.h + * + * S390 version + * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation + * + * Derived from "include/asm-i386/semaphore.h" + * (C) Copyright 1996 Linus Torvalds + */ + +#ifndef _S390_SEMAPHORE_H +#define _S390_SEMAPHORE_H + +#include <asm/system.h> +#include <asm/atomic.h> +#include <linux/wait.h> + +struct semaphore { + atomic_t count; + int sleepers; + wait_queue_head_t wait; +}; + +#define __SEM_DEBUG_INIT(name) + +#define __SEMAPHORE_INITIALIZER(name,count) \ +{ ATOMIC_INIT(count), 0, __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \ + __SEM_DEBUG_INIT(name) } + +#define __MUTEX_INITIALIZER(name) \ + __SEMAPHORE_INITIALIZER(name,1) + +#define __DECLARE_SEMAPHORE_GENERIC(name,count) \ + struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) + +#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) +#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0) + +static inline void sema_init (struct semaphore *sem, int val) +{ + *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val); +} + +static inline void init_MUTEX (struct semaphore *sem) +{ + sema_init(sem, 1); +} + +static inline void init_MUTEX_LOCKED (struct semaphore *sem) +{ + sema_init(sem, 0); +} + +asmlinkage void __down_failed(void /* special register calling convention */); +asmlinkage int __down_failed_interruptible(void /* params in registers */); +asmlinkage int __down_failed_trylock(void /* params in registers */); +asmlinkage void __up_wakeup(void /* special register calling convention */); + +asmlinkage void __down(struct semaphore * sem); +asmlinkage int __down_interruptible(struct semaphore * sem); +asmlinkage int __down_trylock(struct semaphore * sem); +asmlinkage void __up(struct semaphore * sem); + +static inline void down(struct semaphore * sem) +{ + if (atomic_dec_return(&sem->count) < 0) + __down(sem); +} + +static inline int down_interruptible(struct semaphore * sem) +{ + int ret = 0; + + if (atomic_dec_return(&sem->count) < 0) + ret = __down_interruptible(sem); + return ret; +} + +static inline int down_trylock(struct semaphore * sem) +{ + int ret = 0; + + if (atomic_dec_return(&sem->count) < 0) + ret = __down_trylock(sem); + return ret; +} + +static inline void up(struct semaphore * sem) +{ + if (atomic_inc_return(&sem->count) <= 0) + __up(sem); +} + +/* rw mutexes (should that be mutices? =) -- throw rw + * spinlocks and semaphores together, and this is what we + * end up with... + * + * The lock is initialized to BIAS. This way, a writer + * subtracts BIAS ands gets 0 for the case of an uncontended + * lock. Readers decrement by 1 and see a positive value + * when uncontended, negative if there are writers waiting + * (in which case it goes to sleep). + * + * The value 0x01000000 supports up to 128 processors and + * lots of processes. BIAS must be chosen such that subl'ing + * BIAS once per CPU will result in the long remaining + * negative. + * + * In terms of fairness, this should result in the lock + * flopping back and forth between readers and writers + * under heavy use. + * + * -ben + */ +struct rw_semaphore { + atomic_t count; + volatile unsigned int write_bias_granted; + volatile unsigned int read_bias_granted; + wait_queue_head_t wait; + wait_queue_head_t write_bias_wait; +}; + +#define RW_LOCK_BIAS 0x01000000 + +#define __RWSEM_DEBUG_INIT /* */ + +#define __RWSEM_INITIALIZER(name,count) \ +{ ATOMIC_INIT(count), 0, 0, __WAIT_QUEUE_HEAD_INITIALIZER((name).wait), \ + __WAIT_QUEUE_HEAD_INITIALIZER((name).write_bias_wait) \ + __SEM_DEBUG_INIT(name) __RWSEM_DEBUG_INIT } + +#define __DECLARE_RWSEM_GENERIC(name,count) \ + struct rw_semaphore name = __RWSEM_INITIALIZER(name,count) + +#define DECLARE_RWSEM(name) __DECLARE_RWSEM_GENERIC(name,RW_LOCK_BIAS) +#define DECLARE_RWSEM_READ_LOCKED(name) __DECLARE_RWSEM_GENERIC(name,RW_LOCK_BIAS-1) +#define DECLARE_RWSEM_WRITE_LOCKED(name) __DECLARE_RWSEM_GENERIC(name,0) + +static inline void init_rwsem(struct rw_semaphore *sem) +{ + atomic_set(&sem->count, RW_LOCK_BIAS); + sem->read_bias_granted = 0; + sem->write_bias_granted = 0; + init_waitqueue_head(&sem->wait); + init_waitqueue_head(&sem->write_bias_wait); +} + +extern void __down_read_failed(int, struct rw_semaphore *); +extern void __down_write_failed(int, struct rw_semaphore *); +extern void __rwsem_wake(int, struct rw_semaphore *); + +static inline void down_read(struct rw_semaphore *sem) +{ + int count; + count = atomic_dec_return(&sem->count); + if (count < 0) + __down_read_failed(count, sem); +} + +static inline void down_write(struct rw_semaphore *sem) +{ + int count; + count = atomic_add_return (-RW_LOCK_BIAS, &sem->count); + if (count < 0) + __down_write_failed(count, sem); +} + +/* When a reader does a release, the only significant + * case is when there was a writer waiting, and we've + * bumped the count to 0: we must wake the writer up. + */ +static inline void up_read(struct rw_semaphore *sem) +{ + int count; + count = atomic_inc_return(&sem->count); + if (count == 0) + __rwsem_wake(count, sem); +} + +/* releasing the writer is easy -- just release it and + * wake up any sleepers. + */ +static inline void up_write(struct rw_semaphore *sem) +{ + int count; + count = atomic_add_return(RW_LOCK_BIAS, &sem->count); + if (count >= 0 && count < RW_LOCK_BIAS) + __rwsem_wake(count, sem); +} + +#endif |